Retarded cement



LN'HVIIHLR I fi ented Mar. 30,1954 UNITED STATES PATENT OFFICE RETARDED CEMENT Norman 0. Ludwig, Chicago, 111., usignor to Universal Atlas Cement Company, a corporation of Indiana No Drawing. Application January 7, 1952,

Serial Manual...-

1 4 Claims. (Cl. 106-93) 2 This invention is particularly concerned with in the cement solution, especially the calcium hydraulic cements. for example, Portland and compounds. decre Portland type cements, used in the cementing of nllwells having a depth in the neighborhood of eel u e amo o ecrease varies ac- 6,000 to 14,000 feet or greater. In cementing these 5 cord gto the grade and type of carboxymethyl- Y wells the cement is mixed with water to form a cellulose andinsome instances precipitation of all pumpable neat slurry which is pumped into the the carboxymethylcellulose addition results so well and down the hole into the place where it is that all of its retarding eifect is lost. I have found I desired to have it harden. Due to the .depth of that the effectiveness of the carboxymethylcelthe well-considerable time is required to pump lulose can be increased by the addition of alka the slurry into place. Furthermore. in pumping salts to the cement or cement slurry. B0 orthe cement down through the casing and forcing gm and inorganic alkali salts are effective for it upwardly around the outer surface of the casthis purpose. The following inorganic metal ing or through perforations in the lower end of alkali salts were found to function well: sodium the easing into theiormation desired to be sealed, sulphate (Nazsoi) potassium sulphate (K2804) the slurry will pass through narrow channels and potassium chromate (KzCrzOv) sodium bromide small openings. Also, at these great depths high (NaBr) sodium sulphite (NazSOa) sodium thiotemperatures are encountered. Therefore, sucsulphate (NazSzOs), potassium fluoride (KF), cessful placement of the slurry requires that it potassium nitrate (KNOs), potassium iodide (KI) remain fluid and pumpable at high temperatures and potassium chloride (KCl). However, an for several hours before it begins to harden. It account of cost and compatibiiity with cement has been found that Portland and Portland type and other desirable properties, the alkali sulcement slurries can be retarded so that they phates NazS04 and K2804 are preferred. meet all the above requirements for the satis- The following organic salts were found to funciactory cementing of deepewells by the addition of tion well: potassium acetate (KCiHsOz) potascarbox methlcellulose (CMC) and salts threof slum propionate (KCsHsOa), potassium salicylate within certa ieIFe' Ii R s as ii'sc'lo'sei ii my (KC'zI-IsOs), potassium benzoate (KClHsOa), and Patent No. 2,427,683. dated September 23, 1947. potassium lactate (KCsHsOs).

One of the objects of my invention is to provide Carboxymethylcellulose and .its salts may be a cement of the above typ in which the carboxypresent in amounts ranging from .05 to .75% by methylcellulose addition is made more effective. weight of the dry cement and the alkali salt may Another object of the invention is to provide a be present in an amount between .25 and 1.30% slurry of the above cement. I by weight of the dry cement.

These and other objects will be more apparent Tests were made using the cements identified after referring to the following description. 5 in Table I below:

Table L-Chemical composition and fineness Oxide Analysis, Percent Cement 510: Also: 1M0: Loss CaO M30 MnO B0:

Alkalies, Percent N O a: Cement Equiv.

0:5 0:8 01A 04A! 0380; K0 NmO Total Fineness rmm sza w er Me Bu ace, Percent cmJ/g.

Sample A Y 75.7 1,195 SompieB 63.7 1,155 Sample 0 71. 9 1,105

Ihave founcfbat dissolved mu and mad I In making the tests, the inorganic salts and the 4 cement to which the carboxymethylcellulose had previously been added. Halliburton consistcmeter tests were made on the slurries at a temperature of 200 F. according to the method given in A. P. I. Code 32, First Edition. The following tables give the results of the tests.

Table II.Data showing retarding efl'ect of one CMC product plus K2804 and NazSO: 1. SAMPLE A CEMENT Halliburton Consistometer Tests at 200 F., 40%

Slurry-Slurry Viscosity in Poises at Time Thickening Percent Percent Indl ted Grade OMG 0M0 Salt salt 'iig n e 2 SAMPLE B CEMENT 3. SAMPLE C CEMENT Table [IL-Data showmg retarding efl'ect of three addztional CMC products plus K2804 and 11112504 SAMPLE C CEMENT Halibut)?! consistiosxgitlg Tfiftspag 200 tF., 410"? urryany oses a e k um Percent Percent Indicated 8 3 Grade of CMC Salt Time,

0M0 But Hr.:Min.

.09 8 18 22 26 62 2:05 .09 0.25 9 18 26 9 8 8 8 5:55 09 0. 9 4 4 8 8 8 8 +6 hr .09 0. 8 4 4 11 12 12 12 14 +6 hr .09 1.0) 10 9 9 9 9 13 14 4:10. .09 8 16 21 21 2:00. 09 0. 25 8 22 18 8 7 7 7 7 +6 hr. .09 0.50 20 8 8 8 8 8 8 8 +6 hr. 09 0.75 19 8 6 7 7 7 7 7 +6 111. 09 1.00 14 10 8 8 8 8 8 8 +6 hr. 1 15 19 18 20 20 48 2:17. 15 0. 25 10 13 13 13 15 16 40 4:30. .15 0.50 8 8 8 9 11 12 18 4:44. .15 0. 75 16 17 18 22 22 24 70 4:06. .15 1.00 12 14 17 19 19 19 74 4:03. .09 8 18 22 26 62 2:05. .09 0.613 9 8 8 8 7 7 9 4:50. .09 0.921 15 9 9 8 8 8 14 4:43. .09 1.227 12 6 6 6 6 6 9 4:50. .09 8 16 21 26 100 2:00. .09 0.613 9 13 8 8 8 8 8 8 6:30. .09 0.921 24 13 9 8 8 8 8 12 5:55. .09 1.227 12 10 9 8 8 8 8 10 5:50. .15 9 18 20 20 48 2:17. 15 0. 613 8 10 20 9 9 12 26 4:35. .15 0.921 10 12 12 13 15 15 48 4:20. 15 1. 227 9 14 14 16 16 16 60 4:08.

organic salts Halliburton Cousistometer Tests at 200 F., 40%

giggly-Slurry Viscosity in Poises at Time lndi- Thickening Salt Percent Time,

Hr.:Min. 0 15 0:30 100 2'00 3:00 400 5 00 1. 04 9 9 10 9 9 9 9 8:30 0. 37 9 8 8 8 8 8 8 8 +9200 0. 44 7 l0 10 10 ll 12 12 12 +9:00 0. 87 8 7 8 8 9 9 9 9 +9:00 0. 33 l3 l8 19 22 24 27 34 4:35 0. 36 17 9 9 9 9 9 9 12 +830 0. 59 14 8 8 8 8 8 8 8 7:15 K01 0.26 12 10 9 9 9 9 9 9 +7:30 Pot. Acetate, KCrHaO: 0.35 12 8 8 9 8 8 8 9 +6:30 Pot. Propionate, KCSHSOI. 0. 46 10 8 8 9 8 8 8 9 +6280 Pot. Sallcylate. KC1H:0:.- 0. 62 50 38 32 28 24 32 21 26 5:50 Pot. Benzoafe, KC1H O; 0.75 15 12 14 l6 l6 18 22 19 +6:30 Pot. Lactate, KCzHsOi 0. 45 36 22 l8 17 20 22 22 20 +6530 None 8 18 22 26 62 2:05

ed alkali saltalone increase the thickening time or the cement. wnenusiag' the cement of Sample A theaddition 0f .07% of carboxymethylcellulose No. 90 increased the thickening time from 1 hr. 5 min. to 3 hr. 35 min. The further addition of either NazS04 or K2804 increased the thickening time to between 4 hr. 20 min. and 5 hr. 7 min. When using the cement of Sample B, the addition of 09% of carboxymethylcellulose No. 90 did not increase the thickening time, but the further addition of either Na2SO4 or K2804 increased the thickening time from 1 hr. 33 min. to between 1 hr. 54 min.and 4 hr. The thickening time of the cement of Sample C was increased only slightly (from 1 hr. 15 min. to approximately 2 hr.) by

- the addition of No. 90 carboxymethylcellulose,

No. 70 low viscosity carboxymethylcellulose, NHACMC and No. 12 carboxymethylcellulose. However, when alkali sulphates were added thereto, the same proportions of the carboxymethylcellulose products increased the thickening time to between approximately 3 and 6 hrs.

While several embodiments of my invention have been described, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. A cement capable of iorming a fluid slurry when mixed with water, said cement having a retarded set at temperatures above atmospheric, said cement comprising a Portland cement containing water soluble alkalis and additives including from .05 to .75% by weight of the dry cement of at least one of the group consisting ofcarboxvmethylcellulose and salts of carboxymethylcellulose, and from .25 to 1.30% by weight 01' the dry cement of at least one water soluble alkali metal salt to increase the retarding effect of the carboxymethylcellulose and salts of carboxymethylcellulose.

2. ,A cement capable of iorming a fluid slurry when mixed with water, said cement having a retarded set at temperatures above atmospheric, said cement comprising a Portland cement containlng water soluble alkalis and additives including from .05 to .75% by weight of the dry cement of at least one of the group consisting of carboxymethylcellulose and salts of carboxymethylcellulose, and from ,25 to 1.30% by weight of the dry cement of at least one water soluble alkali sulphate from the group consisting of sodium sulphate and potassium sulphate to increase the retarding effect of the carboxymethylcellulose" an sa s o xyme y ce u ose.

3. A hydraulic cement slurry having a retarded set at temperatures above atmospheric, comprising Portland cement containing water soluble alkalis, water, and additives including from .05 to .'75% by weight of the dry cement of at least one of the group consisting of carboxymethylcellulose and salts of carboxymethylcellulose, and from .25 to 1.30% by weight of the dry cement of at least one water soluble alkali metal salt to increase the retarding effect of the carboxymethylcellulose and salts of carboxymethylcellulose.

4. A hydraulic cement slurry having a retarded set at temperatures above atmospheric, comprising Portland cement containing water soluble alkalis, water, and additives including from .05 to .'75% by weight of the dry cement of at least one of the group consisting of carboxymethylcellulose and salts of carboxymethylcellulose, and from .25 to 1.30% by weight of the dry cement of at least one water soluble alkali sulphate from the group consisting of sodium sulphate and potassium sulphate to increase the retarding effect of the carboxymethylcellulose and salts of carboxymethylcellulose.

NORMAN C. LUDWIG.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,868,372 Swift July 19, 1932 2,292,616 Dailey Aug. 11, 1942 2,307,270 Hodge Jan. 5, 1943 2,410,390 Paley Oct. 29, 1946 2,427,683 Ludwig Sept. 23, 1947 OTHER REFERENCES Chemistry of Cement and Concrete by F. M. Lea and C. H. Desch (1935), pages 66 and 158. 

1. A CEMENT CAPABLE OF FORMING A FLUID SLURRY WHEN MIXED WITH WATER, SAID CEMENT HAVING A RETARDED SET AT TEMPERATURE ABOVE ATMOSPHERIC, SAID CEMENT, COMPRISING A PORTLAND CEMENT CONTAINING WATER SOLUBLE ALKALIS AND ADDITIVES INCLUDING FROM .05 TO .75% BY WEIGHT OF THE DRY CEMENT OF AT LEAST ONE OF THE GROUP CONSISTING OF CARBOXYMETHYLCELLULOSE AND SALTS OF CARBOXYMETHYLCELLULOSE, AND FROM .25 TO 1.30% BY WEIGHT OF THE DRY CEMENT OF AT LEAST ONE WATER SOLUBLE ALKALI METAL SALT TO INCREASE THE RETARDING EFFECT OF THE CARBOXYMETHYLCELLULOSE AND SALTS OF CARBOXYMETHYLCELLULOSE. 